Red-light-emitting material based on pyridine imine boron difluoride receptor and preparation method and application of red-light-emitting material

Abstract

The invention discloses a red light emitting material based on a pyridine imine boron difluoride receptor as well as a preparation method and application of the red light emitting material, and belongs to the field of organic photoelectric materials. The red light emitting material based on the pyridine imine boron difluoride acceptor has a structure as shown in a formula I, a nitrogen-containing heterocyclic ring is taken as an electron donor, pyridine imine boron difluoride is taken as an electron acceptor, a D-A-D structure with strong electron donating and electron withdrawing groups is formed, a large space conjugated system is formed, narrow-band system dark red light emission is realized, and the red light emitting efficiency is improved. A non-radiative transition path is reduced, and the luminous efficiency of the material is improved. The compound has proper HOMO energy level and LUMO energy level by regulating and controlling the electron cloud distribution of a molecular front track, is beneficial to matching with each functional layer of a device, reduces the working voltage of the device, and improves the luminous efficiency of the device. Due to the existence of boron difluoride, the conformation of the material is diversified, and under the stimulation of external mechanical force, the material can generate the change of luminescence displacement, so that the material can be applied to an information encryption device.

Description

Technical Field

[0001] This invention belongs to the field of organic optoelectronic materials, and particularly relates to a red light material based on pyridineimine boron difluoride acceptor, its preparation method and application. Background Technology

[0002] Organic light-emitting diodes (OLEDs) have gained widespread application prospects and attracted significant attention from the scientific and industrial communities due to their advantages such as self-illumination, environmental friendliness, fast response speed, low energy consumption, light weight, thinness, foldability, flexibility, wide viewing angle, high color rendering index, and ability to fabricate large-size panels. These advantages have led to their broad application prospects in next-generation lighting, display, and wearable devices. The development of OLED devices has resulted in an increasing demand for OLED luminescent materials. The luminescent layer material is the most crucial component of organic light-emitting devices. Improving the luminescence efficiency of the luminescent layer material, controlling its energy level structure, and enhancing its stability are essential for fabricating high-performance organic light-emitting devices. Current materials still cannot meet production requirements and remain a research hotspot. Furthermore, in the context of the information explosion, information security is paramount. Organic mechanoresponsive luminescent materials can generate contrast luminescence signals under mechanical stimulation, making them highly popular in information storage and encryption. Among these, red light-emitting materials with high solid-state luminescence efficiency are particularly favored due to their strong penetration ability, low excitation energy, and low background interference.

[0003] Thermally activated delayed fluorescence (TADF) materials can convert triplet excitons into singlet excitons through thermally excited antisystem crossing, thus breaking through the theoretical limit of 25% exciton utilization in traditional fluorescent materials, achieving a luminescence quantum efficiency of up to 100%. TADF materials combine the advantages of good stability in organic fluorescent materials and high luminescence efficiency in transition metal complex phosphors. When used in organic electroluminescent devices, the external quantum efficiency of some devices approaches that of phosphorescent devices, representing a significant breakthrough in organic fluorescent devices. Therefore, TADF materials, as a novel class of low-cost, high-efficiency organic light-emitting materials, have attracted great interest from researchers and have broad application prospects.

[0004] Blue and green luminescent materials are sufficient to meet the luminescence performance requirements of organic electroluminescent devices. However, red luminescent materials, due to their small band gap, tend to have overlapping vibrations between the ground and excited states, leading to nonradiative transitions during molecular de-excitation and resulting in low fluorescence quantum yields. Secondly, red luminescent material molecules generally have long conjugated structures; in thin films, the intermolecular distance decreases, and strong π-π interactions are detrimental to luminescence. This reduces the luminescence efficiency of the device, limiting the application of red luminescent materials in OLED devices. Therefore, there are few types of red luminescent materials with high luminescence efficiency, and their emission color tends towards an orange-red hue, making it difficult to achieve deep red light emission.

[0005] Most of the materials reported so far have relatively limited applications, serving only as electroluminescent or information encryption materials, which significantly increases the workload for researchers. Utilizing the same material in multiple applications can effectively improve material utilization and accelerate work efficiency.

[0006] The donor-acceptor structure is crucial for achieving red light emission in TADF materials. To achieve red TADF emission, the commonly used charge transfer strategy employs a donor-acceptor structure. However, these molecules often exhibit distorted structures to form small singlet triplet energy level differences (ΔEST), resulting in low overlap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), leading to low luminous efficiency and limiting their application in organic electroluminescent devices. To improve luminous efficiency, increasing material rigidity and restricting intramolecular rotation can reduce radiative transition paths. Nitrogen-containing heterocycles, as effective and stable electron donor groups, have been widely used in DAD-type red light-emitting materials. However, they still suffer from low luminous efficiency, insufficient redness, and energy level mismatch with other functional layers in electroluminescent devices. Therefore, the selection of donor and acceptor groups is critical to solving these problems. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a red light material based on pyridineimine boron difluoride acceptor, its preparation method and application, wherein the material can achieve high-contrast stimulus-response luminescence.

[0008] To solve the above technical problems, according to one aspect of the present invention, a red light material based on a pyridineimine boron difluoride acceptor is provided, having the structure shown in Formula I: ; Where R is , or .

[0009] According to another aspect of the present invention, a method for preparing the red light material based on the pyridineimine difluoride acceptor described above is provided, comprising the following steps: Step 1: 6(5H)-phenanthrenedione and bromosuccinimide (NBS) are added to N,N-dimethylformamide to carry out a bromination reaction. After the reaction is completed, compound A is obtained.

[0010] Step 2: Phosphorus pentachloride (PCl5) is added to a toluene solution of compound A to carry out a chlorination reaction. After the reaction is complete, compound B is obtained.

[0011] Step 3: 4-Bromo-2-methylpyridine is added to a mixed solvent of diisopropylaminolithium and tetrahydrofuran, and then a tetrahydrofuran solution of compound B is added to carry out an addition reaction. After the reaction is completed, compound C is obtained.

[0012] Step four: Boron trifluoride ether (BF3•OEt2) and triethylamine are added to a toluene solution of compound C to carry out a cyclization reaction, yielding compound D.

[0013]

[0014] Step 5: Compound D, nitrogen-containing heterocyclic compound, palladium catalyst, phosphine ligand catalyst, and organic base undergo a Buchwald-Hartwig coupling reaction in toluene solvent to obtain a red light material with the structure shown in Formula I.

[0015] Furthermore, in step one, the molar ratio of 6(5H)-phenanthrenedione to bromosuccinimide (NBS) is 1:1 to 1.2, the bromination reaction is carried out at room temperature, and the reaction time is 0.5 to 1.5 h.

[0016] Furthermore, in step two, the molar ratio of compound A to phosphorus pentachloride (PCl5) is 1:1 to 1.3; the reaction temperature is 100 to 120 °C; and the reaction time is 18 to 24 h.

[0017] Furthermore, in step three, the molar ratio of 4-bromo-2-methylpyridine to diisopropylaminolithium and compound B is 1:1~1.2:1~1.2; the reaction temperature is room temperature, and the reaction time is 12~16 h.

[0018] Furthermore, in step four, the molar ratio of compound C to boron trifluoride ether and triethylamine is 1:5~10:5~10; the reaction temperature is 100~110 ℃; and the reaction time is 10~12 h.

[0019] Further, in step five, the palladium catalyst is tris(dibenzylacetone)dipalladium, tetra(triphenylphosphine)palladium, or palladium acetate; the phosphine ligand catalyst is tri-tert-butylphosphine tetrafluoroborate or tri-tert-butylphosphine; the organic base is sodium tert-butoxide or potassium tert-butoxide; the molar ratio of compound D to nitrogen-containing heterocyclic compound is 1:2 to 2.2; the molar ratio of compound D to palladium catalyst is 1:0.05 to 0.10; the molar ratio of compound D to phosphine ligand catalyst is 1:0.05 to 0.10; and the molar ratio of compound D to organic base is 1:2 to 3.

[0020] Furthermore, in step five, the reaction temperature is 110℃~115℃, and the reaction time is 12 h~18 h.

[0021] According to another aspect of the present invention, the application of the red light material based on the pyridineimine difluoride acceptor described herein as an organic electroluminescent material is provided.

[0022] According to another aspect of the present invention, an organic electroluminescent device is provided, wherein at least one functional layer comprises the red light material based on the pyridineimine difluoride acceptor described above.

[0023] The red light material based on pyridineimine difluoride boron difluoride acceptor provided by this invention has high electroluminescence efficiency and can achieve deep red light emission, enabling high-contrast stimulus-response luminescence, and thus can be applied to information encryption devices.

[0024] Furthermore, the preparation method of the multifunctional red light material provided by this invention has readily available starting materials, mild reaction conditions, and simple operation steps, which helps to reduce preparation costs. When the compound is applied to vapor deposition devices, it has high brightness and color purity, which is beneficial to the commercial application of the material. Attached Figure Description

[0025] Figure 1 The image shows the doped electroluminescence spectrum of the red light material in Example 1. Figure 2 The image shows the doped electroluminescence spectrum of the red light material in Example 2. Figure 3 The image shows the doped electroluminescence spectrum of the red light material in Example 3. Figure 4 The current efficiency-brightness-EQE relationship diagram of the red light material in Example 1 is shown. Figure 5 The current efficiency-brightness-EQE relationship diagram for the red light material in Example 2 is shown. Figure 6 The current efficiency-brightness-EQE relationship diagram for the red light material in Example 3 is shown. Figure 7 The current density-voltage-brightness relationship diagram for the red light material in Example 1 is shown. Figure 8 The current density-voltage-brightness relationship diagram for the red light material in Example 2 is shown. Figure 9 The current density-voltage-brightness relationship diagram for the red light material in Example 3 is shown. Figure 10 The images show the spectra of the red light material in Example 1 before and after grinding. Figure 11 The images show the spectra of the red light material in Example 2 before and after grinding. Figure 12 The images show the spectra of the red light material in Example 3 before and after grinding. Figure 13 This is a diagram showing the effect of grinding the red light material after its information encryption application in Example 1. Figure 14 This is a diagram showing the effect of grinding the red light material after its information encryption application in Example 2. Figure 15 This is a diagram showing the effect of grinding the red light material after its information encryption application in Example 3. Figure 16 The images show the original effects of the red light material information encryption application in Examples 1, 2, and 3. Detailed Implementation

[0026] A typical embodiment of the present invention provides a red light-emitting material based on a pyridineimine boron difluoride acceptor, having the structure shown in Formula I: ; Where R is , or .

[0027] Specifically, the red light material provided by the present invention has the structure shown in any one of Formula I-1, Formula I-2 and Formula I-3: .

[0028] The red light-emitting material provided by this invention uses a nitrogen-containing heterocyclic electron donor and pyridineimide boron difluoride as an electron acceptor, forming a DAD structure with strong electron-donating and electron-withdrawing groups. This creates a large spatially conjugated system, which is beneficial for achieving narrow-band deep red light emission. The nitrogen-containing heterocyclic electron-donating group and the pyridineimide boron difluoride acceptor group provided by this invention have a rigid structure, which helps reduce non-radiative transition paths and improves the material's luminescence efficiency. The introduction of the pyridineimide boron difluoride acceptor, which has a steric hindrance effect, provides steric hindrance, improving the material's rigidity and charge transfer efficiency. Its excellent electron-withdrawing properties further enhance the material's luminescence efficiency. Furthermore, by controlling the electron cloud distribution of the molecular frontier orbitals, the compound possesses suitable HOMO and LUMO energy levels, which is beneficial for matching with the functional layers of the device, reducing the device's operating voltage, and improving the device's luminescence efficiency. Due to the presence of boron difluoride, the material exhibits diverse conformations and can produce changes in luminescence shift under external mechanical stimulation, enabling the material to be successfully applied to information encryption devices. The multifunctional red light material provided by this invention has an emission wavelength of 620~668 nm and a fluorescence quantum yield of 20.1~25.7%.

[0029] Another typical embodiment of the present invention provides a method for preparing red light materials based on pyridineimine difluoride boron acceptors as described above.

[0030] Step 1: 6(5H)-phenanthrenedione and bromosuccinimide (NBS) are added to N,N-dimethylformamide (DMF) to carry out a bromination reaction. After the reaction is completed, compound A is obtained.

[0031] In this step, the molar ratio of 6(5H)-phenanthrene ketone and bromosuccinimide (NBS) is 1:1 to 1.2, for example: 1:1, 1:1.1, 1:1.2.

[0032] In this step, when adding the 6(5H)-phenanthrene ketone and bromosuccinimide (NBS) to the DMF solvent, the preferred method includes: adding 6(5H)-phenanthrene ketone and NBS to ultra-dry DMF, evacuating and purging with nitrogen three times, stirring and heating to a dissolution temperature of 60~80 °C, for example, 60 °C, 70 °C, and 80 °C; dissolving for 10~15 min, for example, 10 min, 11 min, 12 min, 13 min, 14 min, and 15 min; and dissolving the reactants.

[0033] In this step, the bromination reaction is carried out at room temperature for 0.5–1.5 h; the equation for the bromination reaction is as follows:

[0034] After the bromination reaction is completed, the product is preferably precipitated in deionized water, extracted with dichloromethane, the organic phase is washed with saturated sodium chloride solution and dried with anhydrous magnesium sulfate, filtered, and the organic solvent in the organic phase is distilled under reduced pressure. The crude product is purified by column chromatography to obtain compound A.

[0035] Step 2: Phosphorus pentachloride (PCl5) is added to a toluene solution of compound A to carry out a chlorination reaction. After the reaction is complete, compound B is obtained.

[0036] In this step, the molar ratio of compound A to phosphorus pentachloride (PCl5) is 1:1 to 1.3, for example, 1:1, 1:1.1, 1:1.2, or 1:1.3.

[0037] In this step, the mixing process of phosphorus pentachloride (PCl5), compound A and toluene solvent preferably includes adding PCl5 to an ultra-dry toluene solution of compound A, evacuating and purging nitrogen three times, and stirring and heating to reflux.

[0038] In this step, the chlorination reaction temperature is 100~120 ℃, for example 100 ℃, 110 ℃, 120 ℃, and the reaction time is 18~24 h; the equation for the chlorination reaction is as follows:

[0039] After the chlorination reaction is completed, the reaction system is preferably cooled to room temperature, the solvent is removed by vacuum distillation, a saturated solution of sodium bicarbonate is added to the residue oil for neutralization, dichloromethane is used for extraction, the organic phase is washed with a saturated sodium chloride solution and dried with anhydrous magnesium sulfate, filtered, and the organic solvent in the organic phase is distilled under reduced pressure. The crude product is purified by column chromatography to obtain compound B.

[0040] Step 3: 4-Bromo-2-methylpyridine is added to a mixed solvent of diisopropylaminolithium and tetrahydrofuran, and then a tetrahydrofuran solution of compound B is added to carry out an addition reaction. After the reaction is completed, compound C is obtained.

[0041] In this step, the molar ratio of compound 4-bromo-2-methylpyridine to lithium diisopropylaminodimethylpyridine is 1:1 to 1.2, and the molar ratio of compound 4-bromo-2-methylpyridine to compound B is 1:1 to 1.2.

[0042] In this step, the mixing process of compound B, 4-bromo-2-methylpyridine, and lithium diisopropylamino and tetrahydrofuran solvent preferably includes adding 4-bromo-2-methylpyridine to a mixed solvent of lithium diisopropylamino and ultra-dry tetrahydrofuran, then adding an ultra-dry tetrahydrofuran solution of compound B, evacuating the mixture with nitrogen three times, stirring thoroughly, at a mixing temperature of -78 to -80 °C, and for a mixing time of 1 to 1.5 h.

[0043] In this step, the addition reaction temperature is room temperature, and the reaction time is 12-16 h; the reaction equation for the addition reaction is as follows:

[0044] After the addition reaction is completed, the reaction system is preferably poured into excess water, extracted with dichloromethane solution, the organic phase is washed three times with saturated sodium chloride solution, dried with anhydrous magnesium sulfate, filtered, and the organic solvent in the organic phase is distilled under reduced pressure. The crude product is purified by column chromatography to obtain compound C.

[0045] Step four: Boron trifluoride ether (BF3•OEt2) and triethylamine are added to a toluene solution of compound C to carry out a cyclization reaction, yielding compound D.

[0046]

[0047] In this step, the molar ratio of compound C to boron trifluoride diethyl ether is 1:5~10; the molar ratio of compound C to triethylamine is 1:5~10.

[0048] In this step, the mixing process of adding boron trifluoride ether (BF3•OEt2) and triethylamine to the toluene solution of compound C preferably includes: adding BF3•OEt2 and triethylamine to the ultra-dry toluene solution of compound C, evacuating and purging nitrogen three times, and stirring and heating to the reflux temperature.

[0049] In this step, the cyclization reaction temperature is 100~110 ℃, and the reaction time is 10~12 h; the equation for the cyclization reaction is as follows:

[0050] After the cyclization reaction is completed, the mixture is preferably cooled to room temperature, the reaction solution is poured into water, extracted with dichloromethane, the organic phase is washed with saturated sodium chloride solution and dried with anhydrous magnesium sulfate, filtered, and the organic solvent in the organic phase is distilled under reduced pressure. The crude product is purified by column chromatography to obtain compound D.

[0051] Step 5: Compound D, nitrogen-containing heterocyclic compound, palladium catalyst, phosphine ligand catalyst, and organic base undergo a Buchwald-Hartwig coupling reaction in toluene solvent to obtain a red light material with the structure shown in Formula I.

[0052] In this step, the nitrogen-containing heterocyclic compound may be acridine, phenothiazine, or phenotoxazine; the palladium catalyst is tris(dibenzylacetone)dipalladium, tetraphenylphosphine palladium, or palladium acetate; the phosphine ligand catalyst is tri-tert-butylphosphine tetrafluoroborate or tri-tert-butylphosphine; and the organic base is sodium tert-butoxide or potassium tert-butoxide.

[0053] The molar ratio of compound D to nitrogen-containing heterocyclic compound is 1:2 to 2.2; the molar ratio of compound D to palladium catalyst is 1:0.05 to 0.10; the molar ratio of compound D to phosphine ligand catalyst is 1:0.05 to 0.10; and the molar ratio of compound D to organic base is 1:2 to 3.

[0054] In this step, the mixing process of compound D, nitrogen-containing heterocyclic compound, palladium catalyst, phosphine ligand catalyst and organic base in toluene solvent preferably includes: adding compound D, nitrogen-containing heterocyclic compound, palladium catalyst, phosphine ligand catalyst and organic base to ultra-dry toluene solution, evacuating and purging nitrogen three times, stirring and heating to the temperature of Buchwald-Hartwig coupling reaction.

[0055] In this step, the Buchwald-Hartwig coupling reaction temperature is 110℃~115℃, and the reaction time is 12 h~18 h; the equation for the Buchwald-Hartwig coupling reaction is as follows:

[0056] After the coupling reaction is completed, the present invention preferably pours the reaction solution into ice water, extracts it with dichloromethane, washes the organic phase with saturated sodium chloride solution and dries it with anhydrous magnesium sulfate, filters it, distills the organic solvent in the organic phase under reduced pressure, and purifies the crude product by column chromatography to obtain the compound with the structure shown in Formula I.

[0057] Another typical embodiment of the present invention provides the application of the red light material described in the above scheme or the red light material prepared by the above scheme as an organic electroluminescent material.

[0058] Based on this, the present invention provides an organic electroluminescent device, wherein at least one functional layer of the organic electroluminescent device comprises the red light material described in the above scheme or the red light material obtained by the preparation method described in the above scheme.

[0059] In this embodiment, the red light material prepared according to the present invention is preferably used as the light-emitting layer, which can be a doped light-emitting layer or an undoped light-emitting layer.

[0060] In this embodiment, the raw materials for preparing the doped luminescent layer preferably further include a host material; the host material preferably includes one or more of 4,4'-N,N'-dicarbazole biphenyl (CBP), 2-(4-diphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene (TPBI), and 3-(4-diphenyl)-5-(4-tert-butylphenyl)-4-(4-ethylphenyl)-1,2,4-triazole (TAZ); the present invention does not have a special limitation on the host material, and commercially available products well known to those skilled in the art can be used. In the present invention, the mass ratio of the red light material based on the pyridineimide boron difluoride acceptor to the host material is preferably 1~30:100. In the present invention, the number of layers of the doped or undoped luminescent layer is preferably ≥1 layer; the thickness of each luminescent layer is preferably 40~50 nm independently.

[0061] In this embodiment, the organic electroluminescent device preferably further includes an electrode layer, which preferably includes an anode layer and a cathode layer; the anode layer preferably includes an anode transparent conductive film shielding glass (ITO) layer; the thickness of the anode layer is preferably 10~60 nm; the cathode layer preferably includes an aluminum layer; the thickness of the cathode layer is preferably 1~4 nm.

[0062] In this embodiment, the organic electroluminescent device preferably further includes a functional layer. The functional layer preferably includes a hole injection layer, a hole transport layer, a hole blocking layer, a light-emitting layer, an electron transport layer, and an electron injection layer, or a hole transport layer, a light-emitting layer, and an electron injection layer. In this invention, the raw material for preparing the hole injection layer is preferably molybdenum oxide (MoO3, HAT-CN), and the raw material for preparing the hole transport layer preferably includes 4,4,4,-tris(carbazole-9-yl)triphenylamine (TCTA); the thickness of the hole transport layer is preferably 40 nm. In this invention, the raw material for preparing the hole blocking layer preferably includes N,N-bis(1-naphthyl)-N,N-diphenyl-(1,1-diaminebiphenyl) (NPB); the thickness of the hole blocking layer is preferably 10-15 nm. In this invention, the raw material for preparing the electron transport layer preferably includes m-tris(phenylbenzimidazole)benzene (TPBI), 4,7-diphenyl-1,10-phenanthroline, or 3-(4-diphenyl)-5-(4-tert-butylphenyl)-4-(4-ethylphenyl)-1,2,4-triazole; the thickness of the electron transport layer is preferably 20-30 nm. In this invention, the raw material for preparing the electron injection layer preferably includes LiF, the thickness of the electron injection layer is preferably 150 nm, and the light-emitting layer is an undoped layer that does not require a host material, with a thickness preferably 20 nm.

[0063] This invention also provides a method for fabricating the organic electroluminescent device described in the above technical solution. The device structure sequentially includes a hole injection layer, a hole transport layer, a hole blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer; or a hole transport layer, a light-emitting layer, an electron injection layer, and a cathode layer, thereby obtaining an organic electroluminescent device. The functional layers are preferably fabricated by vacuum evaporation. This invention does not impose special requirements on the fabrication conditions of each layer, and all are fabrication conditions well known in the art.

[0064] In this invention, the red light material based on pyridineimine boron difluoride acceptor can be used not only in red OLED devices, but also as a signal source to prepare information encryption devices.

[0065] The information encryption device is fabricated using a screen printing apparatus, and the materials used include colorless transparent dyes, inorganic red powders, red fluorescent materials with non-stimuli-responsive luminescence properties, and the red stimulus-responsive luminescent material based on pyridineimine difluoride boron difluoride acceptors provided in this invention.

[0066] The technical solutions claimed in this invention will be further described below through some embodiments. However, the embodiments are for explaining the implementation of the present invention and do not exceed the scope of the subject matter of the present invention. The scope of protection of the present invention is not limited by the embodiments. Unless otherwise specified, the materials and reagents used in this invention can be obtained from commercially available products in the art.

[0067] In the following embodiments, the synthesis methods of compounds of formula A, formula B, formula C and formula D are carried out according to the following steps.

[0068] (1) Synthesis of compound A, 2-bromo-6(5H)-phenanthridine ketone:

[0069] Bromosuccinimide (NBS) (1.0 g, 5.6 mmol) was added to a 25 mL solution of 6(5H)-phenanthrenedione (1.0 g, 5.1 mmol) in DMF. The mixture was stirred under argon atmosphere at 70 °C for 15 minutes under nitrogen purging three times, followed by stirring at room temperature for 1 hour. After the reaction was complete, the product was precipitated in deionized water, extracted with dichloromethane, and the organic phase was washed with saturated sodium chloride solution and dried over anhydrous magnesium sulfate. The mixture was filtered, and the organic solvent in the organic phase was distilled under reduced pressure. The crude product was purified by column chromatography (petroleum ether: ethyl acetate = 5:1) to obtain compound A as a white powder (1.1 g, 78%). 1 H NMR (600 MHz, Chloroform- d ) δ 11.81 (s, 1H), 8.32 (dd, J= 8.4, 1.8 Hz, 1H), 8.20(m, 1H), 7.89 (d, J = 1.8 Hz, 1H), 7.73 (td, J = 7.8, 1.8 Hz, 1H), 7.59 (m,2H), 7.33 (d, J = 8.4 Hz, 1H). MS (MALDI-TOF, m / z):[M] + The calculated value is 274.12, and the measured value is 274.09.

[0070] (2) Synthesis method of compound B, 2-bromo-6-chloro-phenanthridine:

[0071] Phosphorus pentachloride (1.8 g, 8.8 mmol) was added to a toluene (60 mL) solution of compound A (2.0 g, 7.3 mmol). The mixture was evacuated under nitrogen, stirred, and heated to 100 °C for 24 h. After cooling to room temperature, the solvent was removed by vacuum distillation. Sodium bicarbonate and toluene were added to the residue oil for neutralization. The residue was extracted with dichloromethane, and the organic phase was washed with saturated sodium chloride solution and dried over anhydrous magnesium sulfate. The mixture was filtered, and the organic solvent in the organic phase was distilled under reduced pressure. The crude product was purified by column chromatography (petroleum ether: ethyl acetate = 4:1) to obtain compound B as a pale yellow solid (1.9 g, 90%). 1 H NMR (600MHz, Chloroform- d ) δ 8.36 (dd, J = 7.2, 1.2 Hz, 1H), 8.06 (dd, J = 8.4, 1.2Hz, 1H), 7.91 (m, 2H), 7.78 (dd, J = 8.4, 1.8 Hz, 1H), 7.72 (dd, J = 7.8, 1.2Hz, 1H), 7.56 (td, J = 7.8, 1.2 Hz, 1H). MS (MALDI-TOF, m / z):[M] + The calculated value is 292.56, and the measured value is 273.01.

[0072] (3) Synthesis of compound C, 2-bromo-6-(4-bromopyridylmethyl)phenanthridine:

[0073] Under a nitrogen atmosphere and at a controlled temperature of -78 °C, lithium diisopropylamino (4.6 mL, 5.2 mmol) was added dropwise to an ultradry THF solution (50 mL), followed by 4-bromo-2-methylpyridine (0.9 g, 5.2 mmol). The reaction mixture was stirred at -78 °C for 1 h, and then compound B (1.5 g, 5.2 mmol) in THF (80 mL) was added at -10 °C. After stirring at room temperature for 12 hours, the reaction was complete. The reaction mixture was poured into excess water, extracted with dichloromethane solution, and the organic phase was washed three times with saturated sodium chloride solution, dried over anhydrous magnesium sulfate, filtered, and the organic solvent in the organic phase was distilled under reduced pressure. The crude product was purified by column chromatography (petroleum ether: ethyl acetate = 1:1) to give compound C as a yellow solid (0.46 g, 21%). 1 H NMR (600 MHz, Chloroform- d ) δ 8.44 (d, J = 3.6 Hz, 1H), 8.31(dd, J = 8.4, 1.2 Hz, 1H), 8.26 (m, 1H), 7.97 (d, J = 1.8 Hz, 1H), 7.85 (d, J = 8.4 Hz, 1H), 7.77 (dd, J = 8.4, 1.8 Hz, 1H), 7.55 (td, J = 7.2, 1.2 Hz, 1H), 7.49 (dd, J = 7.8, 1.32 Hz, 1H), 7.38 (d, J = 1.8 Hz, 1H), 7.31 (dd, J =3.6, 1.8 Hz, 1H), 4.62 (s, 2H). MS (MALDI-TOF, m / z):[M] + The calculated value is 428.13, and the measured value is 428.11.

[0074] (4) Synthesis method of compound D, 2,6'-dibromopyridineimine boron difluoride

[0075] BF3•OEt2 (1.3 mL, 1.5 g, 11 mmol) and triethylamine (1.5 mL, 1.1 g, 11 mmol) were added at room temperature to a solution of compound C (0.45 g, 1.1 mmol) containing toluene (50 mL). The mixture was purged with nitrogen three times under vacuum and stirred at 100 °C for 12 h. After filtering to remove the precipitate, the solvent was removed using a rotary evaporator. The mixture was extracted with dichloromethane, and the organic phase was washed with saturated sodium chloride solution and dried over anhydrous magnesium sulfate. After filtration, the organic solvent in the organic phase was distilled under reduced pressure. The crude product was purified by column chromatography (petroleum ether: ethyl acetate = 1:1) to obtain compound D as red crystals (0.17 g, 34%). 1 H NMR (600 MHz, Chloroform- d ) δ 8.61 (d, J = 8.4 Hz, 1H), 8.40 (m,1H), 8.32 (d, J = 8.4 Hz, 1H), 7.76 (dd, J = 8.4, 1.2 Hz, 1H), 7.66 (d, J =1.8 Hz, 1H), 7.54 (td, J = 7.8, 1.2 Hz, 1H), 7.53 (s, 1H), 7.44 (m, 3H), 4.48(s, 1H), 4.40 (s, 1H). MS (MALDI-TOF, m / z):[M] + The calculated value is 476.93, and the measured value is 477.03.

[0076] Example 1: Synthesis of Compound 2,6'-Acridinepyridineimine boron difluoride of Formula I-1 The red light material based on pyridineimine difluoride boron difluoride acceptor provided in this embodiment has the structure shown in Formula I-1 below.

[0077]

[0078] Compound D (1 g, 2.1 mmol), 9,9'-dimethylacridine (0.96 g, 4.6 mmol), tris(dibenzylacetone)dipalladium (192.1 mg, 0.21 mmol), tri-tert-butylphosphine tetrafluoroborate (31.9 mg, 0.11 mmol), and sodium tert-butoxide (3.5 g, 3.6 mmol) were added to an ultra-dry toluene solution (30 mL). The mixture was evacuated under nitrogen, heated to 115 °C, and stirred for 12 h to terminate the reaction. The reaction solution was poured into ice water and extracted with dichloromethane. The organic phase was washed with saturated sodium chloride solution and dried over anhydrous magnesium sulfate. After filtration, the organic solvent in the organic phase was distilled under reduced pressure. The crude product was purified by column chromatography (petroleum ether: ethyl acetate = 8:1) to obtain the compound with the structure shown in Formula I-1 as a red powder (1.0 g, 65%). 1 H NMR (600 MHz, Chloroform- d ) δ 8.31 (m, 1H), 8.26 (d, J = 8.4 Hz, 1H), 7.76 (dd, J = 8.4, 1.8 Hz, 1H), 7.53 (m, 2H), 7.41 (td, J = 8.4, 1.2 Hz, 1H), 7.27 (m, 5H), 7.13 (m, 4H), 7.09 (td, J = 7.8, 1.2 Hz, 4H), 7.00 (m, 3H), 6.96 (dd, J = 6.0, 1.8 Hz, 2H), 6.91 (s, 1H), 6.84 (d, J = 1.8 Hz, 1H), 4.43(s, 1H), 4.35 (s, 1H), 1.62(s, 12H). 13 C NMR (150 MHz, Chloroform- d) δ 155.09,155.03, 154.98, 153.47, 153.42, 153.36, 148.27, 143.97, 141.81, 141.43,141.24, 141.01, 140.24, 140.19, 140.13, 138.98, 138.95, 138.93, 138.85,137.45, 130.62, 130.56, 130.50, 130.13, 130.09, 130.06, 128.86, 128.81,128.75, 128.48, 128.35, 128.32, 128.29, 128.21, 127.75, 127.72, 127.69, 126.30, 125.33, 125.20, 125.17, 125.12, 125.11, 122.55, 122.28, 122.23, 122.21, 122.18, 122.15, 121.27, 121.26, 121.15, 121.13, 119.92, 119.89, 119.86, 118.18, 36.76, 36.71, 32.10, 32.07, 32.04, 31.09, 31.05, 31.02. MS(MALDI-TOF, m / z):[M] + The calculated value was 733.69, and the measured value was 733.58. The emission peak of I-1 in toluene solution was located at 628 nm. Ф PL =20.2%), achieving deep red light emission.

[0079] Example 2: Synthesis of Compound 2,6'-Phenothiazine pyridine imine boron difluoride of Formula I-2 The red light material based on pyridineimine difluoride boron difluoride acceptor provided in this embodiment has the structure shown in Formula I-2 below.

[0080]

[0081] Compound D (1 g, 2.1 mmol), phenothiazine (0.91 g, 4.6 mmol), tris(dibenzylacetone)palladium (192.1 mg, 0.21 mmol), tri-tert-butylphosphine tetrafluoroborate (31.9 mg, 0.11 mmol), and sodium tert-butoxide (3.5 g, 3.6 mmol) were added to an ultra-dry toluene solution (30 mL). The mixture was evacuated under nitrogen, heated to 115 °C, and stirred for 12 h to terminate the reaction. The reaction solution was poured into ice water and extracted with dichloromethane. The organic phase was washed with saturated sodium chloride solution and dried over anhydrous magnesium sulfate. After filtration, the organic solvent in the organic phase was distilled under reduced pressure. The crude product was purified by column chromatography (petroleum ether: ethyl acetate = 8:1) to obtain the compound with the structure shown in Formula I-2 as a red powder (0.90 g, 60%). 1 H NMR (600 MHz, Chloroform- d ) δ 8.31 (m, 1H), 8.26 (d, J = 8.4 Hz, 1H), 7.76 (dd, J = 8.4, 1.8 Hz, 1H), 7.53 (m, 2H), 7.42 (m, 1H), 7.33 (m, 13H), 7.18 (m, 4H), 7.00 (d, J = 2.0 Hz, 1H), 6.92 (dd, J = 8.4, 1.8 Hz, 1H), 6.84 (d, J = 1.8Hz, 1H), 4.43 (s, 1H), 4.35 (s, 1H). 13 C NMR (150 MHz, Chloroform- d) δ 155.09,155.03, 154.98, 153.47, 153.42, 153.36, 146.20, 143.88, 143.80, 143.76,143.75, 142.18, 140.24, 140.19, 140.13, 137.45, 130.62, 130.56, 130.50,130.13, 130.09, 130.06, 128.48, 128.35, 128.32, 128.29, 128.21, 127.75,127.72, 127.69, 127.49, 127.35, 127.34, 127.30, 127.24, 127.17, 126.30,125.29, 124.11, 124.08, 124.05, 122.55, 122.20, 122.17, 122.14, 120.34,120.22, 119.88, 119.85, 119.82, 118.12, 116.56, 116.53, 116.48, 116.42,31.09, 31.05, 31.02. MS (MALDI-TOF, m / z):[M] + The calculated value was 713.65, and the measured value was 713.64. The emission peak of I-2 in toluene solution is located at 644 nm (…). Ф PL =22.6%), achieving deep red light emission.

[0082] Example 3: Synthesis of Compound 2,6'-Phenoxazine pyridinium difluoride (Formula I-3) The red light material based on pyridineimine difluoride boron difluoride acceptor provided in this embodiment has the structure shown in Formula I-3 below.

[0083]

[0084] Compound D (1 g, 2.1 mmol), phenoxazine (0.84 g, 4.6 mmol), tris(dibenzylacetone)palladium (192.1 mg, 0.21 mmol), tri-tert-butylphosphine tetrafluoroborate (31.9 mg, 0.11 mmol), and sodium tert-butoxide (3.5 g, 3.6 mmol) were added to an ultra-dry toluene solution (30 mL). The mixture was evacuated under nitrogen, heated to 115 °C, and stirred for 12 h to terminate the reaction. The reaction solution was poured into ice water and extracted with dichloromethane. The organic phase was washed with saturated sodium chloride solution and dried over anhydrous magnesium sulfate. After filtration, the organic solvent in the organic phase was distilled under reduced pressure. The crude product was purified by column chromatography (petroleum ether: ethyl acetate = 8:1) to obtain the compound with the structure shown in Formula I-3 as a red powder (0.83 g, 58%). 1 H NMR (600 MHz, Chloroform- d ) δ 8.31 (m, 1H), 8.26 (d, J = 8.4 Hz, 1H), 7.76 (dd, J = 8.4, 1.8 Hz, 1H), 7.53 (m, 2H), 7.41 (td, J = 8.4, 1.2 Hz, 1H), 7.26 (dd, J = 7.8, 1.8 Hz, 1H), 7.18 (m, 9H), 7.13 (m, 3H), 7.00 (d, J = 2.4 Hz, 1H), 6.92 (dd, J = 8.4, 1.8 Hz, 1H), 6.85 (m, 5H), 4.43 (s, 1H), 4.35 (s, 1H). 13CNMR (125 MHz, Common NMR Solvents) δ 155.10, 155.04, 154.98, 153.47, 153.42,153.36, 147.88, 144.03, 143.98, 143.87, 143.64, 140.24, 140.19, 140.13,137.45, 134.66, 134.62, 134.58, 134.51, 130.62, 130.56, 130.50, 130.14,130.11, 130.08, 128.48, 128.46, 128.43, 128.40, 128.21, 127.75, 127.72,127.69, 126.30, 125.35, 123.94, 123.88, 123.82, 122.55, 122.25, 122.23,122.22, 122.18, 122.12, 119.96, 119.93, 119.89, 118.26, 118.14, 118.09,118.08, 118.06, 115.65, 115.62, 115.57, 31.09, 31.05, 31.02.MS (MALDI-TOF, m / z): [M] + The calculated value was 681.53, and the measured value was 681.55. The emission peak of I-3 in toluene solution was located at 668 nm. Ф PL =25.6%), achieving deep red light emission.

[0085] Performance testing The red-light materials prepared in Examples 1-3 had their photoluminescence (PL) spectra at room temperature measured using a HITICHI-4700 fluorescence spectrophotometer. The electroluminescence (EL) spectra were calibrated at room temperature using a PR-655 photochemical research spectrometer. Figures 1-3 The electroluminescence (EL) spectrum of the red light material used as an emitting layer in OLED devices shows that the electroluminescence curves of the material are all in the red light range, indicating that it can be used as a red light emitting layer in undoped OLED devices.

[0086] The device structure provided by this invention is ITO / MoO3 (3 nm) / HAT-CN (10 nm) / NPB (25 nm) / TCTA (5 nm) / EML (20 nm) / TPBi (45 nm) / LiF (1 nm) / Al (100 nm). ITO glass serves as the substrate, HAT-CN as the hole injection layer, NPB as the hole transport layer, and TCTA as the hole blocking layer. The emissive layer (EML) material mainly comprises three parts: the red light material based on pyridineimide boron difluoride acceptor prepared in Examples 1-3 of this invention, a thermally activated delayed fluorescence sensitizer (NAI-DMAC), and a thermally activated delayed fluorescence host material (DMAC-DPS), with a mass ratio of 0.5:30:100. TPBi serves as the electron transport layer, LiF as the electron injection layer, and Al as the cathode layer. A hole injection layer, a hole transport layer, a hole blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer are sequentially prepared on the surface of the anode layer by vacuum evaporation to obtain a red OLED device. Figures 4-6 The diagram shows the current efficiency-brightness-EQE relationship when the red light-emitting material of this invention is used as the light-emitting layer in the fabrication of doped devices in OLED devices. Figures 7-9 The diagram shows the current density-voltage-brightness relationship when the material of this invention is used as the light-emitting layer in OLED devices to prepare doped devices.

[0087] As shown in the test results of the example, the organic electroluminescent device based on the red light-emitting material I-1 of pyridineimine difluoride acceptor as the light-emitting layer has a turn-on voltage of 3.6 V, a maximum current efficiency of 56.29 cd / A, and a power efficiency of 47.21 m / W; it emits deep red light with a peak position of 628 nm and a maximum brightness of 7370 cd / m². 2 The organic electroluminescent device based on pyridineimide boron difluoride acceptor I-2 as the emitting layer has a turn-on voltage of 3.6 V, a maximum current efficiency of 43.37 cd / A, and a power efficiency of 34.95 m / W; it emits deep red light with a peak at 644 nm and a maximum luminance of 5634 cd / m². 2 The organic electroluminescent device based on pyridineimine difluoride boron difluoride acceptor I-3 as the emitting layer has a turn-on voltage of 3.6 V, a maximum current efficiency of 30.3 cd / A, and a power efficiency of 24.4 m / W; it emits deep red light with a peak position of 664 nm and a maximum brightness of 5538 cd / m². 2 Devices based on compounds I-1 to I-3 have achieved efficient deep red light emission.

[0088] In addition to being used as a light-emitting layer material to prepare OLED devices, the red light material based on pyridineimine difluoride boron difluoride acceptor prepared in this invention can also be used as a signal source to prepare information encryption devices. Figures 13-15 These are images showing the effect of grinding the red light materials obtained in Examples 1, 2, and 3 after information encryption application. Figure 16 The images show the original effect diagrams of the information encryption application of red light materials obtained in Examples 1, 2, and 3.

[0089] The specific implementation method of information anti-counterfeiting encryption device is as follows: The information anti-counterfeiting encryption device includes a screen printing device, an optional red light non-stimulating active luminescent material and a red light stimulating responsive material of pyridineimine difluoride boron difluoride receptor prepared in the embodiments of the present invention, wherein the emission wavelength of the non-stimulating active luminescent material needs to be close to the original wavelength of the red light material obtained in Examples 1, 2 and 3, which is about 575nm~600nm.

[0090] a. Fabricate multiple alphanumeric display panels A using a screen-printed mask; in this example, it is 5 rows and 6 columns. First, print the non-stimuli-responsive luminescent material onto a cardboard using a screen printing machine; b. Then create a number or letter display board B that is the same size as the number and letter display board. First line:

[0091] Second line:

[0092] Third line:

[0093] Fourth line:

[0094] Fifth line:

[0095] c. The red light material obtained in Example 1, 2, or 3 is overprinted onto the cardboard after process a above using a digital or alphabetical display panel B, with the visual color as shown. Figure 16 As shown; d. After forcefully scraping and pressing the cardboard following process c, the visual color corresponding to the red light material obtained in Examples 1, 2, and 3 changes to the following: Figures 13-15 .

[0096] Meaning explanation: such as Figures 13-15The last digit of each line indicates the position of the digit or letter of interest within that line. Consecutive concatenation of these letters or numbers from each line yields the correct encrypted transmission content. In this case, the first line contains the encrypted content "P", the second line "E", the third line "A", the fourth line "C", and the fifth line "E". Therefore, the parsed transmission content in this case is "PEACE". Figures 13-16 This is just an example; you can add rows or columns as needed to create content that requires encrypted transmission.

Claims

1. A red light-emitting material based on a pyridineimine boron difluoride acceptor, characterized in that: It has the structure shown in Equation I: ； Where R is , or .

2. The method for preparing the red light material based on the pyridineimine boron difluoride acceptor as described in claim 1, characterized in that, Includes the following steps: Step 1: 6(5H)-phenanthrenedione and bromosuccinimide are added to N,N-dimethylformamide to carry out a bromination reaction. After the reaction is completed, compound A is obtained. ； Step 2: Phosphorus pentachloride is added to a toluene solution of compound A to carry out a chlorination reaction. After the reaction is complete, compound B is obtained. ； Step 3: 4-Bromo-2-methylpyridine is added to a mixed solvent of diisopropylaminolithium and tetrahydrofuran, and then a tetrahydrofuran solution of compound B is added to carry out an addition reaction. After the reaction is completed, compound C is obtained. ； Step four: Add boron trifluoride diethyl ether and triethylamine to a toluene solution of compound C to carry out a cyclization reaction to obtain compound D; ； Step 5: Compound D, nitrogen-containing heterocyclic compound, palladium catalyst, phosphine ligand catalyst, and organic base undergo a Buchwald-Hartwig coupling reaction in toluene solvent to obtain a red light material with the structure shown in Formula I.

3. The method for preparing red light-emitting materials based on pyridineimine difluoride boron difluoride acceptors according to claim 2, characterized in that: In step one, the molar ratio of 6(5H)-phenanthrenedione to bromosuccinimide is 1:1 to 1.2, the bromination reaction is carried out at room temperature, and the reaction time is 0.5 to 1.5 h.

4. The method for preparing red light-emitting materials based on pyridineimine difluoride boron difluoride acceptors according to claim 2 or 3, characterized in that: In step two, the molar ratio of compound A to phosphorus pentachloride is 1:1 to 1.3; the reaction temperature is 100 to 120 °C; and the reaction time is 18 to 24 h.

5. The method for preparing red light-emitting materials based on pyridineimine difluoride boron difluoride acceptors according to claim 4, characterized in that: In step three, the molar ratio of 4-bromo-2-methylpyridine to lithium diisopropylamino and compound B is 1:1 to 1.2:1 to 1.2; the reaction temperature is room temperature, and the reaction time is 12 to 16 h.

6. The method for preparing red light-emitting materials based on pyridineimine boron difluoride acceptors according to claim 2 or 5, characterized in that: In step four, the molar ratio of compound C to boron trifluoride ether and triethylamine is 1:5~10:5~10; the reaction temperature is 100~110 ℃; and the reaction time is 10~12 h.

7. The method for preparing red light-emitting materials based on pyridineimine difluoride boron difluoride acceptors according to claim 6, characterized in that: In step five, the palladium catalyst is tris(dibenzylacetone)dipalladium, tetra(triphenylphosphine)palladium, or palladium acetate; the phosphine ligand catalyst is tri-tert-butylphosphine tetrafluoroborate or tri-tert-butylphosphine; the organic base is sodium tert-butoxide or potassium tert-butoxide; the molar ratio of compound D to nitrogen-containing heterocyclic compound is 1:2 to 2.2; the molar ratio of compound D to palladium catalyst is 1:0.05 to 0.10; the molar ratio of compound D to phosphine ligand catalyst is 1:0.05 to 0.10; and the molar ratio of compound D to organic base is 1:2 to 3.

8. The method for preparing red light-emitting materials based on pyridineimine difluoride boron difluoride acceptors according to claim 7, characterized in that: In step five, the reaction temperature is 110℃~115℃ and the reaction time is 12 h~18 h.

9. The application of the red light material based on pyridineimine difluoride boron difluoride acceptor as described in claim 1 as an organic electroluminescent material.

10. An organic electroluminescent device, characterized in that: At least one functional layer contains the red light material based on the pyridineimine difluoride boron acceptor as described in claim 1.

Images